In a variety of downhole applications, electric signals are transmitted along the wellbore to or from various sensors and tools. For example, electric signals may be transmitted via conductors positioned in or along well strings, e.g. along drill strings. In drilling applications and other downhole applications, electric signals are sometimes transmitted across components which move relative to each other, e.g. electric signals may be transmitted from a rotationally stationary component to a rotating component. Transmission of electrical signals across moving components creates difficulties in many of these applications.
In some applications, transmission of electric signals across components which move relative to each other can be avoided by placing the sensor/tool above the moving component. In other applications, the signals may be transmitted across the moving components with an electromagnetic telemetry system, such as a short-hop system. However, existing electromagnetic telemetry systems tend to be relatively expensive and are often more complex than desired for downhole drilling applications and other downhole applications.